TheEvolutionofComputers

1Modernelectroniccomputersdidn’tappearuntilthe1940’s.ResearchworkersinAmericaproducedaworkingcomputerin1946.Thefirstmodelswereverybulkybecausetheydependedonvacuumtubessimilartothoseyoumayhaveseeninoldradiosets.Latermachinesusedtransistorsandatpresentweuseintegratedcircuitswhichtakeupverylittle

space.

Now,let’sgetaclearerpictureofthedevelopmentofcomputers.

1.Firstgenerationcomputers

Thefirstgenerationofcomputerswereusedfrom1946to1959.TheywerecharacterizedbythemostprominentfeatureoftheENIACvacuumtubes,andwerelarge,costly,expensivetopowerandoftenunreliable.2Moreover,thevacuumtubeswerefairlylarge,andtheygeneratedsomuchheatthatspecialairconditioninghadtobeinstalledtocoolthem.

2.Secondgenerationcomputers

Thesecondgenerationofcomputersspannedtheyearsfrom1959to1964.Themostnotablechangewasthattransistorsreplacedvacuumtubes.3Thetransistorallowedthedevelopmentofmorepowerful,morereliableandlessexpensivecomputersthatwouldoccupylessspaceandgiveofflessheatthandidcomputersusingvacuumtubes.

Inaddition,thesecondgenerationcomputersweregivenauxiliarystorage,sometimescalledexternalorsecondarystorage.Datawerestoredoutsidethecomputeroneithermagnetictapesormagneticdisks.Usingmagnetictapesormagneticdisksforinputandoutputoperationsincreasedthespeedofthecomputer.

3.Third-generationcomputers

Thethird-generationcomputerslastedfrom1964to1971.4Thethird-generationismarkedchieflybythedevelopmentofintegratedcircuits,whichreplacedtransistors.Withintegratedcircuits,hundredsofelectricalcomponentscouldbeincludedononesiliconchiplessthanone-eighth-inchsquare.Therefore,thecomputersbecameevensmallerwhiletheirmemorycapacitiesbecamelarger.

Thethird-generationcomputersworkedsoquicklythattheyprovidedthecapabilitytorunmorethanoneprogramconcurrently(multiprogramming).Forexample,atanygiventimethecomputermightbeprintingpayrollchecks,acceptingorders,andtestingprograms.

4.Fourth-generationcomputers

From1971tothepresent,wehavethefourth-generationcomputers.Mostcomputervendorsclassifytheircomputersasbeingfourth-generationcomputers,andafewevencalltheirs“fifth-generation”.Thefirstthreegenerationswerecharacterizedbysignificanttechnologicalbreakthroughsinelectronicsfirsttheuseofvacuumtubes,thentransistors,andthenintegratedcircuits.

Chipcircuitryhasbecomeincreasinglyminiaturizedinfourthgenerationcomputers.Largescaleintegration(LSI)circuits,featuringthousandsofelectroniccomponentsonasinglesiliconchip,becamecommonduringthe1970s.

Microprocessorchipscanmanagethefunctionsofthecomputer,performcalculations,andcontrolotherdevicesjustlikelargecomputers.

5Themodernmicrocomputerconsistsofamicroprocessorandotherdenselypackedchipsusedforstorageandinput/outputoperations,allofwhicharemorepowerfulthanlargecomputersofearliergenerations.

Now,LSIhasalreadyprogressedintoVLSI(VeryLargeScaleIntegration),whichmeansevenmorecapabilitiesinevensmallerpackages.NewWords

bulkyadj.大的,容量大的,體積大的prominentadj.突出的;顯著的,卓越的costly

adj.貴重的,昂貴的unreliableadj.不可靠的span

v.橫越;n.跨度,跨距,范圍generatevt.產(chǎn)生,發(fā)生componentn.成分;adj.組成的,構(gòu)成的notable

adj.值得注意的,顯著的,著名的concurrentlyadv.并發(fā)地,同時(shí)發(fā)生地payrollcheckn.工資單ordern.定單,次序,順序,命令;vt.命令,訂購,定制vendorn.銷售商,賣主breakthroughn.突破largescaleadj.大規(guī)模的,大范圍的,大批的integrationn.集成(化),整體化,綜合denselyadv.密集地,濃密地,濃厚地miniaturizevt.使小型化PhrasesandExpressions

auxiliarystorage輔助存儲(chǔ)器(或稱外部存儲(chǔ)器)magneticdisk磁盤memorycapacity存儲(chǔ)器容量classify…as分成(為)……類vacuumtube真空管,電子管siliconchip硅片chipcircuitry芯片電路multiprogramming多道程序設(shè)計(jì)TheExplanationofDifficultStatements

1.Modernelectroniccomputersdidn’tappearuntilthe1940’s.

分析:not…until:直到……才……,比如下例:

Hedidn’tbegintodohishomeworkuntilhismotherreturned他直到他媽媽回來才開始做作業(yè)。

句意:現(xiàn)代的電子計(jì)算機(jī)直到20世紀(jì)40年代才問世。

2.Moreover,thevacuumtubeswerefairlylarge,andthey

generatedsomuchheatthatspecialair-conditioninghadtobe

installedtocoolthem.

分析:so…that…:如此……以致于……，that后面接結(jié)果狀語從句。再如:

ThecaseissoheavythatIcan’tliftit.

這個(gè)箱子這么重,我拎不起來。

句意:此外,體積龐大的真空管產(chǎn)生很大的熱量,必須安裝特殊的空調(diào)來降溫。

3.Thetransistorallowedthedevelopmentofmorepowerful,

morereliableandlessexpensivecomputersthatwould

occupylessspaceandgiveofflessheatthandidcomputers

usingvacuumtubes.

分析:句中hatwouldoccupylessspaceandgiveofflessheat

thandidcomputersusingvacuumtubes是computers的定語從句,進(jìn)一步說明computers的性能。

句意:使用晶體管可以制造出功能更強(qiáng)、性能更可靠、價(jià)格更便宜的計(jì)算機(jī),它與真空管計(jì)算機(jī)相比體積小,功耗也小。

4.Thethirdgenerationismarkedchieflybythe

developmentofintegratedcircuits,whichreplaced

transistors.

分析:句中whichreplacedtransistors為integratedcircuits的定語從句。

句意:第三代計(jì)算機(jī)以集成電路取代晶體管為主要標(biāo)志。

5.Themodernmicrocomputerconsistsofamicroprocessor

andotherdenselypackedchipsusedforstorageand

input/outputoperations,allofwhicharemorepowerfulthan

largecomputersofearliergenerations.

分析:consistsof:由……組成。句中usedforstorageandinput/outputoperations是denselypackedchips的定語。而句中allofwhicharemorepowerfulthanlargecomputersofearliergenerations是Themodernmicrocomputer的定語從句。句意:微處理器和其它用于存儲(chǔ)和輸入/輸出操作的集成芯片相結(jié)合,構(gòu)成了現(xiàn)代微型計(jì)算機(jī)。微型計(jì)算機(jī)比前幾代大型計(jì)算機(jī)的功能更為強(qiáng)大。ExercisesⅠ.Choosethebestanswers:(1)Thefourthgenerationofcomputers______________.

A.usetransistors

B.useLSI-circuits

C.arecharacterizedbysignificanttechnological

breakthroughsinartificialintelligence

D.usevacuumtubes(2)Mostmicrocomputertodayarebasedonadesigndevelopedby_____________.

A.Apple

B.NEC

C.IBM

D.Compaq(3)Whetheracomputerispowerfuldependsonits______________.

A.applicationsoftwareB.memorycapacity

C.operationalsoftwareD.CPU’sclockspeed(4)Aseriesofinstructionswrittenforacomputertoperformspecifictasksiscalled______________.

A.softwareB.aprogram

C.afileD.thedataⅡ.TranslatethefollowingwordsandexpressionsintoEnglish:(1)電子管(2)晶體管(3)磁帶機(jī)(4)磁盤機(jī)(5)微處理器(6)大規(guī)模集成電路Ⅲ.TranslatethefollowingsentencesintoEnglish,using“anadjectiveclause”ineachsentence:(1)這是我祖父經(jīng)常曬太陽的花園。(2)這家汽車旅館不是我們?cè)谡业哪穷惵灭^。(3)我們需要一種儀器,它的型號(hào)一定要小。(4)我看了好幾座房子,大多不很合適。(5)此事正在調(diào)查,調(diào)查結(jié)果不久就會(huì)公布。ReadingMaterials

Memory(Ⅰ)

Themicrocomputer’smemoryconsistsofmainmemoryandsecondarystorage.

MainMemory

Themainmemoryofmostcomputersiscomposedofrandomaccessmemory(RAM).Theprogrammer(throughaprogram,ofcourse)canreadtoorwritefromtheRAM.InputdatacanbestoredinRAM,overwritinganddestroyinggtheexistingcontentsoftheselectedbytesorwords.Oncethedataarein,theycanbereadandmanipulatedbytheprocessor,andresultscanbewrittentoothermemorylocations.Finally,thecontentscanbesenttoanoutputdevice.Whenaprogramisfinished,anewprogramcanbecopiedintotheRAM,againoverwritingtheoldoneintheprocess.ThecontentsofRAMareeasytochange.

Usually,RAM’sflexibilityisanadvantage,butoccasionallyitcanbeaproblem.Consider,forexample,theautomatictellerterminalusedinmanybanks.Theyarecontrolledbysmallcomputerwhich,inturn,arecontrolledbyprograms.Acleverprogrammermightbeabletomodifyoneofthoseprogramstogivefreeaccesstocertainaccounts.Needlesstosay,thebankcouldnottoleratesuchchanges.Thebankneedsaprogramthatcanbereadbytheprocessor,butnotmodified.Suchprogramsarestoredinreadonlymemory(ROM).AnothergoodexampleofaROMbasedprogramistheBIOSprogramfoundinmanymicrocomputers.Asthenameimplied,ROMis“permanent”memorythatcanberead,butnotwritten.NewWordsandExpressions

consistof與“becomposedof”意思相似,由……組成word

n.字overwritev.覆蓋automatictellerterminal自動(dòng)終端(出納)機(jī)flexibilityadj.靈活性toleratev.準(zhǔn)許ExercisesChoosethebestanswer:(1)Asmallsectionofthemainmemory,whichisusedforholding

permanentlystoreddataandonlyallowsreadaccessbythe

CPUiscalled______________.

A.RAMB.ROM

C.DOSD.Diskette(2)ROMandRAMaretheacronymsfor______________

respectively.

A.randomaccessmemoryandreadonlymemory

B.readonlymemoryandrandomaccessmemory

C.registerandreadonlymemory

D.registerandrandomaccessmemory

(3)______________doesn’tloseitscontentswhenyouturn

offthecomputer.

A.RAM

B.ROM

C.TheCPU

D.Cache(4)Eachbasicphysicalstorageunitinmainmemoryisassigneda

unique______________,calleditsaddress.

A.number

B.byte

C.capacity

D.bitMemory(Ⅱ)

SecondaryStorage

Mainmemoryonthecomputerisusedtostoreinstructionsanddatatemporarilywhiletheinstructionsarebeingexecutedanddataarebeingprocessed.Inmostapplications,however,theseinstructionsanddatamustbestoredelsewherewhentheyarenotbeingusedbecausemainmemoryisnotlargeenoughtostoretheinstructionsanddataforallapplicationsatonetime.Secondarystorageunitsareusedinmainmemoryofthecomputer.

Oneadvantageofacomputeristhatoncedatahavebeenentered,theycanbestoredonthemachineandaccessedrepeatedly.Generatingaddresslabelsforamagazineisagoodexample.Insteadofretypingallthelabelinformationforeachedition,subscriberdataneedonlybeinputonce,stored,andthenaccessedfromstoragewhenevernecessary.Programsprovideanotherexample.Likethesubscriberdata,theyarestoredonthecomputerandaccessedasneede